Compact sheet cutter for a document reproduction machine

Abstract

A compact sheet feeding and cutting apparatus is disclosed which is particularly suitable for retrofitting to an existing document reproduction machine. The sheet feeding and cutting components are located within a common housing which can be mechanically attached to an existing machine. In one embodiment, no electrical connections are required between the reproduction machine and the feeding and cutting apparatus. A sheet cutting length is entered into local memory and controls the operation of a dc stepper motor in a sheet cutting mode and a sheet feeding mode. The motor is reversed and operates in a sheet feeding mode to drive feed rollers causing the sheet to unroll from a supply roll. The motor is operatively connected to the drive feed rollers and to the sheet cutter through separate, one-way clutches. The sheet is fed from the roll at a faster speed than the speed of sheet travel within the reproduction machine as it advances to a transfer station. This speed mismatch periodically creates a buckle in the moving sheet which contacts a switch causing it to open and close. The switch thus controls an on/off operation of the motor changing it from a sheet feeding mode into a sheet cutting mode.

What is claimed is: 
     
       1. A document reproduction machine of the type having a moving photoreceptive surface; a charging station for placing a charge on the photoreceptive surface; an exposure station for forming an electrostatic latent image on the photoreceptive surface; a developing station for developing the electrostatic latent image with toner particles; a transfer station for transferring the developed image to a copy sheet; and a fusing station for fusing the developed image onto a sheet media, wherein the fusing station includes an input system for advancing sheet media at a first rate, said document reproduction machine further including a sheet cutter, comprised of: a bi-directional drive motor;   a motor driven feed roller for advancing sheet media toward the input system;   a roller clutch for selectively engaging said feed roller to said drive motor;   a buckle sensor for sensing a minimum size buckle in the sheet media;   a motor driven sheet cutter disposed between said feed roller and said input system, said sheet cutter for cutting the sheet media when said sheet cutter is driven by a motor;   a sheet cutter clutch for selectively engaging said sheet cutter to said drive motor; and   a sheet media length circuit for generating a cut signal when a predetermined length of sheet media has advanced from said feed roller;   wherein said sheet cutter clutch engages said sheet cutter to said drive motor upon the occurrence of a cut signal;   wherein said roller clutch engages said feed roller to said drive motor when said buckle sensor does not sense a minimum size buckle;   wherein said sheet media advances toward the input system at a second rate which is greater than said first rate when said feed roller is driven by said drive motor, whereby an expanding buckle is formed in the sheet media;   wherein said hi-directional drive motor rotates in a first direction when said sheet cutter clutch is engaged; and   wherein said bi-directional drive motor rotates in a second direction when said roller clutch is engaged.   
     
     
       2. The document reproduction machine according to claim 1, wherein said bi-directional drive motor stops advancing the sheet media after the buckle expands to a predetermined size.